net/netfilter/nfnetlink_acct.c

   1 /*
   2  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   3  * (C) 2011 Intra2net AG <http://www.intra2net.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation (or any later at your option).
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/atomic.h>
  14 #include <linux/netlink.h>
  15 #include <linux/rculist.h>
  16 #include <linux/slab.h>
  17 #include <linux/types.h>
  18 #include <linux/errno.h>
  19 #include <net/netlink.h>
  20 #include <net/sock.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/nfnetlink.h>
  24 #include <linux/netfilter/nfnetlink_acct.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  28 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  29
  30 static LIST_HEAD(nfnl_acct_list);
  31
  32 struct nf_acct {
  33         atomic64_t              pkts;
  34         atomic64_t              bytes;
  35         unsigned long           flags;
  36         struct list_head        head;
  37         atomic_t                refcnt;
  38         char                    name[NFACCT_NAME_MAX];
  39         struct rcu_head         rcu_head;
  40         char                    data[0];
  41 };
  42
  43 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
  44 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
  45
  46 static int
  47 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
  48              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
  49 {
  50         struct nf_acct *nfacct, *matching = NULL;
  51         char *acct_name;
  52         unsigned int size = 0;
  53         u32 flags = 0;
  54
  55         if (!tb[NFACCT_NAME])
  56                 return -EINVAL;
  57
  58         acct_name = nla_data(tb[NFACCT_NAME]);
  59         if (strlen(acct_name) == 0)
  60                 return -EINVAL;
  61
  62         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
  63                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  64                         continue;
  65
  66                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  67                         return -EEXIST;
  68
  69                 matching = nfacct;
  70                 break;
  71         }
  72
  73         if (matching) {
  74                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  75                         /* reset counters if you request a replacement. */
  76                         atomic64_set(&matching->pkts, 0);
  77                         atomic64_set(&matching->bytes, 0);
  78                         smp_mb__before_atomic();
  79                         /* reset overquota flag if quota is enabled. */
  80                         if ((matching->flags & NFACCT_F_QUOTA))
  81                                 clear_bit(NFACCT_OVERQUOTA_BIT,
  82                                           &matching->flags);
  83                         return 0;
  84                 }
  85                 return -EBUSY;
  86         }
  87
  88         if (tb[NFACCT_FLAGS]) {
  89                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
  90                 if (flags & ~NFACCT_F_QUOTA)
  91                         return -EOPNOTSUPP;
  92                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
  93                         return -EINVAL;
  94                 if (flags & NFACCT_F_OVERQUOTA)
  95                         return -EINVAL;
  96
  97                 size += sizeof(u64);
  98         }
  99
 100         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
 101         if (nfacct == NULL)
 102                 return -ENOMEM;
 103
 104         if (flags & NFACCT_F_QUOTA) {
 105                 u64 *quota = (u64 *)nfacct->data;
 106
 107                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
 108                 nfacct->flags = flags;
 109         }
 110
 111         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
 112
 113         if (tb[NFACCT_BYTES]) {
 114                 atomic64_set(&nfacct->bytes,
 115                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
 116         }
 117         if (tb[NFACCT_PKTS]) {
 118                 atomic64_set(&nfacct->pkts,
 119                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
 120         }
 121         atomic_set(&nfacct->refcnt, 1);
 122         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
 123         return 0;
 124 }
 125
 126 static int
 127 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 128                    int event, struct nf_acct *acct)
 129 {
 130         struct nlmsghdr *nlh;
 131         struct nfgenmsg *nfmsg;
 132         unsigned int flags = portid ? NLM_F_MULTI : 0;
 133         u64 pkts, bytes;
 134         u32 old_flags;
 135
 136         event |= NFNL_SUBSYS_ACCT << 8;
 137         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 138         if (nlh == NULL)
 139                 goto nlmsg_failure;
 140
 141         nfmsg = nlmsg_data(nlh);
 142         nfmsg->nfgen_family = AF_UNSPEC;
 143         nfmsg->version = NFNETLINK_V0;
 144         nfmsg->res_id = 0;
 145
 146         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 147                 goto nla_put_failure;
 148
 149         old_flags = acct->flags;
 150         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 151                 pkts = atomic64_xchg(&acct->pkts, 0);
 152                 bytes = atomic64_xchg(&acct->bytes, 0);
 153                 smp_mb__before_atomic();
 154                 if (acct->flags & NFACCT_F_QUOTA)
 155                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
 156         } else {
 157                 pkts = atomic64_read(&acct->pkts);
 158                 bytes = atomic64_read(&acct->bytes);
 159         }
 160         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
 161             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
 162             nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
 163                 goto nla_put_failure;
 164         if (acct->flags & NFACCT_F_QUOTA) {
 165                 u64 *quota = (u64 *)acct->data;
 166
 167                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
 168                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota)))
 169                         goto nla_put_failure;
 170         }
 171         nlmsg_end(skb, nlh);
 172         return skb->len;
 173
 174 nlmsg_failure:
 175 nla_put_failure:
 176         nlmsg_cancel(skb, nlh);
 177         return -1;
 178 }
 179
 180 static int
 181 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 182 {
 183         struct nf_acct *cur, *last;
 184
 185         if (cb->args[2])
 186                 return 0;
 187
 188         last = (struct nf_acct *)cb->args[1];
 189         if (cb->args[1])
 190                 cb->args[1] = 0;
 191
 192         rcu_read_lock();
 193         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 194                 if (last) {
 195                         if (cur != last)
 196                                 continue;
 197
 198                         last = NULL;
 199                 }
 200                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 201                                        cb->nlh->nlmsg_seq,
 202                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 203                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 204                         cb->args[1] = (unsigned long)cur;
 205                         break;
 206                 }
 207         }
 208         if (!cb->args[1])
 209                 cb->args[2] = 1;
 210         rcu_read_unlock();
 211         return skb->len;
 212 }
 213
 214 static int
 215 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 216              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 217 {
 218         int ret = -ENOENT;
 219         struct nf_acct *cur;
 220         char *acct_name;
 221
 222         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 223                 struct netlink_dump_control c = {
 224                         .dump = nfnl_acct_dump,
 225                 };
 226                 return netlink_dump_start(nfnl, skb, nlh, &c);
 227         }
 228
 229         if (!tb[NFACCT_NAME])
 230                 return -EINVAL;
 231         acct_name = nla_data(tb[NFACCT_NAME]);
 232
 233         list_for_each_entry(cur, &nfnl_acct_list, head) {
 234                 struct sk_buff *skb2;
 235
 236                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 237                         continue;
 238
 239                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 240                 if (skb2 == NULL) {
 241                         ret = -ENOMEM;
 242                         break;
 243                 }
 244
 245                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 246                                          nlh->nlmsg_seq,
 247                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 248                                          NFNL_MSG_ACCT_NEW, cur);
 249                 if (ret <= 0) {
 250                         kfree_skb(skb2);
 251                         break;
 252                 }
 253                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 254                                         MSG_DONTWAIT);
 255                 if (ret > 0)
 256                         ret = 0;
 257
 258                 /* this avoids a loop in nfnetlink. */
 259                 return ret == -EAGAIN ? -ENOBUFS : ret;
 260         }
 261         return ret;
 262 }
 263
 264 /* try to delete object, fail if it is still in use. */
 265 static int nfnl_acct_try_del(struct nf_acct *cur)
 266 {
 267         int ret = 0;
 268
 269         /* we want to avoid races with nfnl_acct_find_get. */
 270         if (atomic_dec_and_test(&cur->refcnt)) {
 271                 /* We are protected by nfnl mutex. */
 272                 list_del_rcu(&cur->head);
 273                 kfree_rcu(cur, rcu_head);
 274         } else {
 275                 /* still in use, restore reference counter. */
 276                 atomic_inc(&cur->refcnt);
 277                 ret = -EBUSY;
 278         }
 279         return ret;
 280 }
 281
 282 static int
 283 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 284              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 285 {
 286         char *acct_name;
 287         struct nf_acct *cur;
 288         int ret = -ENOENT;
 289
 290         if (!tb[NFACCT_NAME]) {
 291                 list_for_each_entry(cur, &nfnl_acct_list, head)
 292                         nfnl_acct_try_del(cur);
 293
 294                 return 0;
 295         }
 296         acct_name = nla_data(tb[NFACCT_NAME]);
 297
 298         list_for_each_entry(cur, &nfnl_acct_list, head) {
 299                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 300                         continue;
 301
 302                 ret = nfnl_acct_try_del(cur);
 303                 if (ret < 0)
 304                         return ret;
 305
 306                 break;
 307         }
 308         return ret;
 309 }
 310
 311 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 312         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 313         [NFACCT_BYTES] = { .type = NLA_U64 },
 314         [NFACCT_PKTS] = { .type = NLA_U64 },
 315         [NFACCT_FLAGS] = { .type = NLA_U32 },
 316         [NFACCT_QUOTA] = { .type = NLA_U64 },
 317 };
 318
 319 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 320         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 321                                             .attr_count = NFACCT_MAX,
 322                                             .policy = nfnl_acct_policy },
 323         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 324                                             .attr_count = NFACCT_MAX,
 325                                             .policy = nfnl_acct_policy },
 326         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 327                                             .attr_count = NFACCT_MAX,
 328                                             .policy = nfnl_acct_policy },
 329         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 330                                             .attr_count = NFACCT_MAX,
 331                                             .policy = nfnl_acct_policy },
 332 };
 333
 334 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 335         .name                           = "acct",
 336         .subsys_id                      = NFNL_SUBSYS_ACCT,
 337         .cb_count                       = NFNL_MSG_ACCT_MAX,
 338         .cb                             = nfnl_acct_cb,
 339 };
 340
 341 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 342
 343 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 344 {
 345         struct nf_acct *cur, *acct = NULL;
 346
 347         rcu_read_lock();
 348         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 349                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 350                         continue;
 351
 352                 if (!try_module_get(THIS_MODULE))
 353                         goto err;
 354
 355                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 356                         module_put(THIS_MODULE);
 357                         goto err;
 358                 }
 359
 360                 acct = cur;
 361                 break;
 362         }
 363 err:
 364         rcu_read_unlock();
 365         return acct;
 366 }
 367 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 368
 369 void nfnl_acct_put(struct nf_acct *acct)
 370 {
 371         atomic_dec(&acct->refcnt);
 372         module_put(THIS_MODULE);
 373 }
 374 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 375
 376 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 377 {
 378         atomic64_inc(&nfacct->pkts);
 379         atomic64_add(skb->len, &nfacct->bytes);
 380 }
 381 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 382
 383 static void nfnl_overquota_report(struct nf_acct *nfacct)
 384 {
 385         int ret;
 386         struct sk_buff *skb;
 387
 388         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 389         if (skb == NULL)
 390                 return;
 391
 392         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
 393                                   nfacct);
 394         if (ret <= 0) {
 395                 kfree_skb(skb);
 396                 return;
 397         }
 398         netlink_broadcast(init_net.nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
 399                           GFP_ATOMIC);
 400 }
 401
 402 int nfnl_acct_overquota(const struct sk_buff *skb, struct nf_acct *nfacct)
 403 {
 404         u64 now;
 405         u64 *quota;
 406         int ret = NFACCT_UNDERQUOTA;
 407
 408         /* no place here if we don't have a quota */
 409         if (!(nfacct->flags & NFACCT_F_QUOTA))
 410                 return NFACCT_NO_QUOTA;
 411
 412         quota = (u64 *)nfacct->data;
 413         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
 414                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
 415
 416         ret = now > *quota;
 417
 418         if (now >= *quota &&
 419             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
 420                 nfnl_overquota_report(nfacct);
 421         }
 422
 423         return ret;
 424 }
 425 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
 426
 427 static int __init nfnl_acct_init(void)
 428 {
 429         int ret;
 430
 431         pr_info("nfnl_acct: registering with nfnetlink.\n");
 432         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 433         if (ret < 0) {
 434                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 435                 goto err_out;
 436         }
 437         return 0;
 438 err_out:
 439         return ret;
 440 }
 441
 442 static void __exit nfnl_acct_exit(void)
 443 {
 444         struct nf_acct *cur, *tmp;
 445
 446         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 447         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 448
 449         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 450                 list_del_rcu(&cur->head);
 451                 /* We are sure that our objects have no clients at this point,
 452                  * it's safe to release them all without checking refcnt. */
 453                 kfree_rcu(cur, rcu_head);
 454         }
 455 }
 456
 457 module_init(nfnl_acct_init);
 458 module_exit(nfnl_acct_exit);